US Army Corps of Engineers - Federal Energy Regulatory ... Safety USACE.pdf · US Army Corps of Engineers One Corps Serving The Army and the Nation UNCLASSIFIED General Provisions

US Army CorpsUS Army Corpsof Engineersof Engineers

One Corps Serving The Army and the Nation

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USACE Seismic Safety AssessmentUSACE Seismic Safety Assessment

2006 Northwest Dam Safety Regional ForumFebruary 14-15, 2006

Portland, Oregon



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General Provisions for EQ General Provisions for EQ Design and EvaluationDesign and Evaluation

• EM 1110-2-1806, EQ Design and Evaluation for Civil Works Projects, 31 Jul 95, for new projects and evaluation of existing projects.

• Scope– Ground Motions– Site Characterization– Structural Response– Potential Hazards– Report Requirements



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Project Hazard PotentialProject Hazard Potential

• Appendix B, Hazard Potential Classification• Critical Features are structures, natural site

conditions, operation equipment and utilities at high hazard projects where failure during or immediately following an EQ could result in a loss of life.

• EM 1110-2-2100, Stability Analysis of Concrete Structures



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Design of New ProjectsDesign of New Projects

• ER 1110-2-1150, Engineering and Design of Civil Works Projects

• Analysis is performed in phases in order of increasing complexity.

• Shall include assessments of potential EQ motions and project features to ensure acceptable performance during and after design events.

• Level of design is dependent upon whether or not seismic loading controls the design, complexity of project, and the consequences of losing project service or control of the pool.



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Evaluation of Existing Evaluation of Existing ProjectsProjects

• EC 1110-2-6061, Safety of Dams-Policies and Procedures, 30 Apr 04

• Initiated by the following circumstances:– Performance inconsistent with the design intent during a

major EQ.– Alteration which changes load conditions.– Advance in state-of-the-art.– Change in project operations impact seismic resistance– Conducted a minimum every 15 years.

• Prioritized by Portfolio Risk Analysis



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Dam Safety Assurance Dam Safety Assurance ProgramProgram

• Provides for special cost sharing per Sec. 1203 of WRDA 1986.

• Allows modifications to completed dams to eliminate safety concerns pertaining to hydrologic and seismic deficiencies.

• Feasibility Type Report



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Dam Safety Assurance Dam Safety Assurance Program (Cont.)Program (Cont.)

• EC 1110-2-6061, Appendix G• Part I-Format and Content of Dam Safety

Assurance Program• Part II-Seismic Safety Evaluation Process for

Embankment Dams and Foundations• Part III-Seismic Safety Evaluation Process for

Concrete Structures and Foundations• Part IV-Hazard Potential Classification



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Dam Safety Assurance Dam Safety Assurance Program (Program (Con.tCon.t))

• Evaluations performed in phases with increasing complexity– Seismic Safety Review (SSR)– Phase I Special Studies-– Phase II Special Studies

• Policy Compliance & Criteria Reviews • Portfolio Risk Assessment updates• Central funding for phases following SSR



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Estimating Ground MotionsEstimating Ground Motions

• ETL 1110-2-301, Interim Procedure for Specifying EQ Motions, 26 Aug 83

• Standard Seismic Studies– Based on preliminary ground motion values,

structural analyses, and soil liquefaction assessments to determine if seismic loadings control.

– DEQAS, Design EQ Analysis System.



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Estimating GM (Cont.)Estimating GM (Cont.)

• Site Specific Studies– Deterministic Seismic Hazard Analysis (DHSA)– Probabilistic Seismic Hazard Analysis (PHSA)

• Deterministic assessment compared with published data to assess a specified time period.

– Specific ground motion-structure interactions provided in engineering manuals.

• Draft EM 1110-2-6000, Selection of Design EQ



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Design EarthquakeDesign Earthquake

• Maximum Credible EQ (MCE)-the greatest EQ that can be reasonably be generated by a specific source. Determined by DSHA.

• Maximum Design EQ (MDE)-the maximum level of ground motion for which a structure is designed. (DSHA or PSHA.)

• Operating Basis EQ (OBE)-the EQ that can be reasonably expected to occur with a 50% probability of exceedence during the service life. (PSHA)



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Key EQ Guidance DocumentsKey EQ Guidance Documents

• ER 1110-2-1806, Earthquake Design and Evaluation for Civil Works Projects, 31 July 1995

• ETL 1110-2-301, Interim Procedure for Specifying Earthquake Motions, 26 Aug 83

• EC 1110-2-6061, Safety of Dams-Policy and Procedures, 30 Apr 04

• Draft EM 1110-2-6000, Selection of Design EQ• Draft EM 1110-2-6001, Seismic Stability of Earth and Rock Fill

Dams• EM 1110-2-6050, Response Spectra and Seismic Analysis for

Concrete Hydraulic Structures, 30 Jun 99• EM 1110-2-6051, Time History Dynamic Analysis of Concrete

Hydraulic Structures, 22 Dec 03



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Concrete and Steel Hydraulic Concrete and Steel Hydraulic StructuresStructures--Performance and Performance and

Load CriteriaLoad Criteria

• Should respond elastically to the OBE with no disruption to service.

• Can respond inelastically to the MDC event, which may result in significant structural damage and limited disruption of services, but should not collapse or endanger lives.

• For critical structures, the MDE=MCE.• OBE=Usual Loading Condition• MCE=Extreme Loading Condition



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Concrete and Steel Hydraulic Concrete and Steel Hydraulic StructuresStructures--Seismic Analysis Seismic Analysis

ProgressionProgression



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Key Structural Design Key Structural Design GuidanceGuidance

• EM 1110-2-2200, Gravity Dam Design, 30 Jun 95• EM 1110-2-2201, Arch Dam Design, 31 May 94• EM 1110-2-2400, Structural Design and Evaluation of

Outlet Works, 2 Jun 03• EM 1110-2-6050, Response Spectra and Seismic

Analysis for Concrete Hydraulic Structures, 30 Jun 99• EM 1110-2-6051, Time History Dynamic Analysis of

Concrete Hydraulic Structures, 22 Dec 03• EC 1110-2-6058, Stability Analyses of Concrete

Structures, 30 Nov 03



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EM 1110EM 1110--22--2200, Gravity 2200, Gravity Dam DesignDam Design

• Stability requirements• Static and Dynamic Stress Analysis• Temperature Control of Mass Concrete• Evaluation Criteria• Use of Roller Compacted Concrete



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Gravity Dam Stability and Gravity Dam Stability and Stress CriteriaStress Criteria



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EM 1110EM 1110--22--2201, Arch Dam 2201, Arch Dam DesignDesign

• Special Considerations for Abutments and Foundations

• Loading Combinations• Details on Dynamic Seismic Analysis• 3D-Dam-Water-Foundation Interaction• Criteria for Static and Dynamic Performance

Evaluation



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EM 1110EM 1110--22--2400, Structural 2400, Structural Design and Evaluation of Outlet Design and Evaluation of Outlet

WorksWorks

Chapter 4, Seismic Design and Evaluation of Intake Tower, Design Considerations:

• Loading Conditions• Design of Reinforcements• Design Earthquake• Stability Requirements• Displacement Based Procedure Analysis for

Evaluation



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EM 1110EM 1110--22--2400, Structural 2400, Structural Design and Evaluation of Outlet Design and Evaluation of Outlet

Works (Cont.)Works (Cont.)

• Appendices– Design Example– Two Mode Approximate Procedure– Hydro Dynamic Added Mass of Water Inside and

Out– Rotational Stability of Intake Tower



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EM 1110EM 1110--22--6050, Response 6050, Response Spectra and Seismic Analysis of Spectra and Seismic Analysis of Concrete Hydraulic StructuresConcrete Hydraulic Structures

• Introduction and Methodology of Seismic Analysis of Concrete Hydraulic Structures (CHS)

• Design Criteria for CHS• Structural Modeling and Analysis for CHS• Interpretation of Results



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EM 1110EM 1110--22--6050, Response 6050, Response Spectra and Seismic Analysis of Spectra and Seismic Analysis of Concrete Hydraulic Structures Concrete Hydraulic Structures

(Cont.)(Cont.)• Earthquake Ground Motions• Developing Response Spectra using PHSA• Equal Hazard Spectra• Design Response Spectra



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EM 1110EM 1110--22--6051, Time6051, Time--History History Dynamic Analysis for Concrete Dynamic Analysis for Concrete

Hydraulic StructuresHydraulic Structures

• Procedure for linear elastic time-history dynamic analysis

• Qualitative estimate of the damage• EQ input acceleration time-history• Examples

– Arch Dam and Gravity Dam– Intake Tower– W-Frame Lock



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EM 1110-2-2100, Stability Analysis of Concrete Structures

• Table 3-1, Load Conditions and Probabilities• Table 3-3, Required Factors of Safety for

Critical Structures• Table 3-4, Required Factors of Safety for All

Structures• Table 3-5, Requirements of the Locations for

All Structures



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Embankments, Slopes, and Embankments, Slopes, and FoundationsFoundations

• Draft EM 1110-2-6001, Dynamic Stability of Earth and Rock Fill Dams

• Pool Elevation at 90% duration of the highest seasonal or normal pool, whichever governs.

• Selecting Design EQ and Ground Motions• Analyses for New and Existing Dams and Foundations• Validation Processes• Highlights Areas of Concern and Recommendations



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Post Construction ReportsPost Construction Reports

• Foundation Completion Report• Embankment Materials and Performance

Report• Concrete Materials Report



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Research NeedsResearch Needs

• For Ground Motions– EQ Hazard Estimation– Site Characterization

• For Concrete and Steel Structures– Constitutive Behavior and Material Parameters for Dynamic

loads– Lift Joints and Foundation Interaction– Improved Analysis Procedure Mode of Failure for Intake

Towers– Cyclic Loading Test for Gravity Dams– Tainter Gate Pier Ductility and Seismic Performance



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Research Needs (Cont.)Research Needs (Cont.)

• For Embankments and Foundations– Validation of Deformation Technologies– Partially Saturated Soils– Residual Strength– Fine Grained Soils– Large Penetration Testing– 3-D Effects



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Points of ContactPoints of Contact

• Headquarters– David Pezza, PE, Embankment Guidance– Jack Berezniak, PE, Ground Motion Guidance– Anjana Chudgar, PE, Structural Guidance

• ERDC– Joe Koester, PhD, PE, Embankment Performance– Mike Sharp, PhD, PE, Geotechnical Numerical Analyses– Enrique Matheu, PhD, PE, Structural Numerical Analyses– Don Yule, PE, Ground Motions and DEQAS Software

• Field– Dale Munger, PE, Draft EM 1110-2-6001– Jeff Schaefer, PhD, PE, Portfolio Risk Analyses



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Questions?Questions?